1. Field of the Invention
The present invention relates to a printer and, more particularly, to a printer whose structure is improved so as to print a picture without leaving margins on the top and bottom of a sheet of paper.
2. Description of the Related Art
Generally, a thermal printer comprises a thermal printing head with a heating element, and a film-shaped ribbon coated with ink. The thermal printer has a transfer structure in which, with the ribbon placed between a sheet of paper and the thermal printing head, ink sublimated by the thermal printing head in a predetermined pattern is delivered onto the paper. Particularly, for full-color printing, a color thermal transfer printer performs a printing operation three times for the color-separated image of yellow, magenta and cyan, respectively.
In such a printer using an ink ribbon on which three (or four) sublimated dyes for yellow, magenta and cyan (or including black) are sequentially coated on one sheet, for every revolution of a drum, the beginning of a predetermined color portion must be searched according to a printing signal and coincide with the initial printing position of the paper.
Referring to FIG. 1 schematically illustrating a conventional printer, a drum 2 is rotatably mounted. A paper cassette 6 is provided under the drum 2. A thermal printing head 1 and an ink ribbon 7 are placed above the drum 2. A plurality of guide rollers 3a, 3b and 3c are provided on the circumference of drum 2. When conveyed from the cassette 6 to the drum 2, a sheet of paper 4 is delivered counterclockwise while making contact with the drum 2 by the guide rollers 3a and 3b. When the leading edge of the paper 4 is compressed by guide roller 3c located beyond the summit S' of the drum 2, the drum 2 stops rotating, and the thermal printing head 1 is lowered by a lift so as to press the paper 4 and the ink ribbon 7. In this state, when the drum 2 rotates, a picture is printed on the paper 4.
As shown in FIG. 1, however, the conventional printer does not print pictures within a section S between the leading edge of paper 4 and the initial compressing position of the thermal printing head 1. This creates a leading edge margin in a printed paper, resulting in a poor appearance.